The present invention relates to test equipment for testing multiple functions of telephone line communication equipment and more particularly with testing telephone line communication equipment which comprise an automatic utility meter reading system which interrogates a utility meter interface device over telephones lines which, in turn, communicates utility usage data by sending a series of pulses of an audio tone over the telephone line.
The test apparatus of the present invention can best be understood by referring to co-pending applications Ser. No. 543,372, filed Oct. 19, 1983 for A Centerpoint Automatic Meter Reading System, Ser. No. 544,110, filed Oct. 21, 1983 for A Multiplexer System for an Automatic Meter Reading, and Ser. No. 502,201, filed June 8, 1983 for A Meter Interfacing Unit for Utility Meter Reading System. These co-pending applications describe in detail an automatic meter reading system for which the present test apparatus is particularly suited. Such an automatic meter reading system employs a multiplexing system which multiplexes signals on a plurality of telephone lines in a central location. The multiplexing system sends out interrogate signals over the plurality of telephone lines which are received by meter interface devices connected to the individual telephone lines, These meter interface devices, in response to receiving a particular distinct interrogation signal from the multiplexing system, send utility usage data over the telephone line to which they are connected. The utility usage data is received from a utility metering device which monitors the usage of such commodities as water, electricity or gas.
A serious need existed to test any of the component parts of such automatic meter reading systems for proper or improper operation including the central telephone office equipment, the line communications channel and the subscriber installations. In order to test the component parts of the system completely with the present invention, the present invention must be able to simulate the functions of several of the components in the system. Thereby, any suspected component or components can be tested using only the present invention for the testing.
To simulate the component parts of the automatic meter reading system requires that a test system be able to simulate a telephone line which includes the normal voltage found on a telephone line, for example, ON-HOOK, non-ringing voltage, plus the frequency response of a telephone line to audio tones or other signals sent over it. Also, such a test system must be able to simulate the operation of the subscriber's utility meter reading apparatus including the utility meter's configuration of sending usage data to the meter interface device responsive to commands therefrom. As well, a suitable test set must be able to simulate the operation of the meter interface device including responding to a particular distinct interrogation signal over a telephone line and the consequent sending of the utility usage data received from the utility meter. In addition, it is desirable that the test system be able to simulate the operation of any multiplexing system used including the sending of the interrogation signals and receiving the utility usage data. Of course, the test set must be able to simulate any combination of the components parts of the automatic meter reading system.
There is test equipment which is intended to test for improper operation of telephone lines and telephone line equipment and there is test equipment which is used to test various functions of telephone communications equipment; but, there has been no known single piece of test apparatus which can test a subscriber's installation, a line and central office equipment from either end of the system. It is common to find test equipment which is dedicated to testing a particular function of piece of equipment, but, nowhere has it been known to put the equivalent of an entire automatic meter reading system in a single box so that the entire system can be tested from this single box as is done in the present invention.
Putting the equivalent of the entire automatic meter reading system in a single box gives the present invention its unique features. The test apparatus can completely test any combination of components of the automatic meter reading system and test all of its own internal functions by arranging the simulators of the individual functions in the same manner as the entire system would be arranged. Thus, a fool proof self-test can be performed.